Seismic Insights into Swarm VS20060202.1: Kilauea Flank Activity in Hawaii

The region surrounding Volcano, Hawaii, lies on the southeastern flank of Kilauea volcano, part of the Hawaiian hotspot chain. This hotspot has driven volcanic island formation for millions of years through a mantle plume beneath the Pacific Plate. Kilauea ranks among Earth's most active volcanoes, with persistent eruptions and associated seismicity linked to magma intrusion and movement along rift zones.

Seismic swarms in this area typically reflect shallow crustal adjustments from dike propagation or volcanic unrest. Depths often remain under 10 km, consistent with the brittle-ductile transition in basaltic rock. Historical records document recurrent swarms tied to Kilauea's dynamic plumbing system, underscoring the interplay between tectonics and volcanism.

Swarm VS20060202.1 initiated at 21:16 on 1 February 2006 and concluded at 12:21 on 9 March 2006. Centered 6 km SSW of Volcano, it produced 821 earthquakes over 855 hours and 5 minutes. This episode aligns with patterns of episodic unrest on Kilauea's south flank.

Analysis of the first 100 events reveals predominantly low-magnitude activity. Magnitudes ranged from 0.8 to 2.4, with the majority between 1.0 and 1.8. Depths clustered at 0–3 km, though occasional events reached 9 km. Early events on 1–2 February showed rapid succession, including multiple magnitude-1.3 quakes at shallow depths near 1–2 km. By 3–5 February, slight increases in magnitude appeared, such as events of 2.4, 2.3, and 2.2, often at 1–2 km depth. Timing indicated clustering during nighttime and early morning hours, with no strong correlation to deeper events beyond 5 km.

These characteristics suggest fluid-driven processes at shallow levels, typical for Kilauea swarms. No events exceeded magnitude 3, indicating limited energy release compared to larger tectonic sequences elsewhere.

Since 1 January 2000, 17 swarms have occurred in the region. Annual counts include three in 2000, one in 2001, eight in 2003, four in 2004, and one in 2005. This frequency highlights ongoing volcanic influence on local seismicity.

Such swarms contribute to monitoring efforts by the Hawaiian Volcano Observatory, aiding eruption forecasting. Continued observation remains essential given Kilauea's history of flank instability and potential for larger events.

References

USGS Hawaiian Volcano Observatory reports on Kilauea seismicity.
Internal SeismoSight classification for swarm VS20060202.1 parameters and event data.